A number of problems can arise when outages occur within an electrical power system. One kind of problem, called voltage collapse, is a cascading loss of stability. The loss of stability typically originates in one or more subsystems of the electrical power system (caused by an equipment outage or increased load), which in turn overloads additional power system components. Voltage collapse can also be caused by an equipment outage due to relaying actions, failure of equipment or failure of control. Typically, voltage collapse leads to a blackout or brownout where customers are no longer provided with the power they desire. Another type of voltage problem, called loss of voltage stability, is the inability of the generation, transmission, and distribution system to supply enough power to satisfy customer demand after a disturbance, increased load or a change in operating conditions without an uncontrollable and progressive decrease in voltage. The source of these instability problems is within and between components in the electrical power system that deliver electrical power to customers. A third problem, called local blackout, occurs when the power network is pushed to its physical limits. This phenomenon can be caused by numerous factors, some of which are 1) exhaustion or depletion of reactive supply in the voltage control or reactive supply devices serving the local region or 2) outages of equipment or 3) increased power flow into or within a local region.